Polymerization processes for using dilute multicomponent feeds (law624)

ABSTRACT

The invention relates to a method of forming carbon monoxide-containing polymers from multi-component syngas feeds and at least one vinyl comonomer. Feeds useful in the practice of the invention comprise ethylene in an amount ranging from about 5 to about 40 mole %, carbon monoxide is an amount ranging from about 1 to about 40 mole %, hydrogen in an amount ranging from about 4 to about 55 mole %, carbon dioxide in an amount ranging from about 3 to about 10 mole %, and methane in an amount ranging from about 4 to about 85 mole %. The feed may also include acetylene in an amount ranging up to about 10 mole %. The feed may contain at least one free radical-polymerizable vinyl comonomer, or a cofeed containing such a comonomer can be used.

FIELD OF THE INVENTION

[0001] The invention is directed towards a polymerization process formaking copolymers from feeds of ethylene, carbon monoxide, and at leastone vinyl comonomer, the feeds preferably being derived from hydrocarbonconversion processes.

BACKGROUND OF THE INVENTION

[0002] Ethylene copolymers with CO, and another vinyl comonomer areprepared at high pressure, high temperature from high purity monomerstreams, especially streams having a low hydrogen concentration.

[0003] Multicomponent syngas-type feeds, containing ethylene, carbonmonoxide, hydrogen, carbon dioxide, methane are formed from various gasconversion processes, and are becoming increasingly abundant. Using suchfeeds for polymerization would be beneficial. However, such feeds arenot considered to have sufficient purity for polymerization because theycontain substantial amounts of reactive species such as hydrogen andacetylene.

[0004] There is therefore a need for a process for forming carbonmonoxide containing copolymers from multicomponent feeds.

SUMMARY OF THE INVENTION

[0005] The invention is a method for polymerizing ethylene-carbonmonoxide with at least one vinyl monomer (X). Such polymers may bedesignated E/CO/X. The method comprises forming copolymers undercopolymerization conditions from a feed of ethylene, carbon monoxide,hydrogen, carbon dioxide, methane, and at least one vinyl comonomerselected from the group consisting of free radical polymerizable vinylmonomers.

[0006] More specifically, the feed contains ethylene in an amountranging from about 5 to about 40 mole %, carbon monoxide in an amountranging from about 1 to about 40 mole %, hydrogen in an amount rangingfrom about 4 to about 55 mole %, carbon dioxide in an amount rangingfrom about 3 to about 10 mole %, and methane in an amount ranging fromabout 4 to about 85 mole %. The feed may also include acetylene in anamount ranging up to about 10 mole %.

[0007] Polymerization conditions range in temperature from about 50 toabout 230° C., range in pressure from about 100 to about 30,000 psi, andinclude a radical initiator having an appropriate half-life.

DETAILED DESCRIPTION OF THE INVENTION

[0008] The invention is based on the discovery that ethylene-carbonmonoxide polymerization processes using multicomponent syngas feedsfacilitate copolymerization with other vinyl monomers. For example,ethylene and octene are difficult to copolymerize under free radicalpolymerization conditions. The reactivity ratio for ethylene is 3.1 andthe reactiviy ratio for others is 8. Consequently, both ethylene andoctene would rather homopolymerize than copolymerize. However, when MCSis used as a source of ethylene, incorporation of at least one vinylcomonomer is enabled.

[0009] Without wishing to be bound by any theory, it is believed the ECOradical is more reactive than an ethylene or octene radical would betoward ethylene or octene. Moreover, RCO.radicals cannot add CO. Thusincorporation of octene is facilitated within excluded sequences of CO.Moreover, it is believed that the hydrogen present in such feedsbeneficially acts as a mild chain transfer agent.

[0010] Feeds useful in the practice of the invention comprise at leastone olefinically unsaturated compound in an amount ranging from about 5to about 40 mole %, carbon monoxide in an amount ranging from about 1 toabout 40 mole %, hydrogen in an amount ranging from about 4 to about 55mole %, carbon dioxide in an amount ranging from about 3 to about 10mole %, and methane in an amount ranging from about 4 to about 85 mole%. The feed may also include at least one acetylinically unsaturatedcompound in an amount ranging up to about 10 mole %. The feed maycontain at least one free radical-polymerizable vinyl comonomer, or acofeed containing such a comonomer can be used. Vinyl monomers useful inthe invention include ethylene, α-olefins (C₃ to C₃₀) such as propylene,butene, 1-octene, 1-octadecene, styrene and styrene derivatives such asα-methylstyrene, p-methylstyrene, tetrafloroethylene, vinyl chloride,vinyl acetate, isobutyl vinyl ether, methyl vinyl ketone,1-vinylpyrrolidone, acrylic acid, methacrylic acid, methylacrylate,methylmethacrylate, acrylonitrile, acrylamide, acrolein, allyl alcohol,allyl chloride, allyl acetate, mixtures thereof, and similar materials.While vinyl comonomer concentration in the feed may range from zero ortrace amounts to about 95 mole %, the preferred concentration rangesfrom about 5 mole % to 80 mole %.

[0011] The olefinically unsaturated compounds (i.e., olefins) useful inthe invention typically contain up to 20 carbon atoms, preferably up to10 carbon atoms. They may contain heteroatoms; however, it is preferredthat the olefinically unsaturated compounds are hydrocarbons. Apreferred class of olefinically unsaturated hydrocarbons are aliphaticmono-olefins, in particular α-olefins of which ethylene is particularlypreferred.

[0012] The acetylenically unsaturated compounds useful in this inventionpreferably contain up to 20 carbon atoms, more preferably up to 10carbon atoms. Preferably they are hydrocarbyl compounds, and they mayvary widely in structure. They may also contain heroatoms. Preferably,the acetylenically unsaturated compounds have at most one organic groupattached to the ethynyl groups. More preferably the acetylenicallyunsaturated compound is of the general formula R—C≡CH where R denotes ahydrogen atom or a hydrocarbyl group. Hydrocarbyl groups R may be arylgroups, such as phenyl, 4-methoxyphenyl, 3-chlorophenyl and naphthylgroups, or (cyclo)alkyl groups, such as methyl, ethyl, 2-propyl,2-butyl, cyclohexyl and 2-methylhexyl-1 groups. For example, when the Rgroup is a methyl groupthen the acetylenically unsaturated compound ispropyne, and when the R group is hydrogen then the acetylenicallyunsaturated compound is acetylene. A mixture of acetylenicallyunsaturated compounds may be involved, but a single acetylenicallyunsaturated compound is preferred.

[0013] Feeds used in the practice of the invention contain a combined COand olefin concentration of no more than about 35 mole %. The preferredfeed is derived from hydrocarbon, preferably from gas conversionprocesses, and still more preferably from natural gas conversionprocesses. Oxidative coupling and methane partial oxidation of amethane-containing gas followed by ethane quench are examples of such areaction. A mixture of feeds resulting from such processes is alsowithin the scope of the invention. In addition to carbon dioxide, inertdiluents such as methane can be present in the feed in amounts rangingfrom about 4 mole % to about 85 mole %. Importantly, feeds used in thepractice of the invention may contain up to 55 mole % H₂. The preferredfeed contains 5 to 55 mole % hydrogen, and is formed in amethane-derived hydrocarbon synthesis reaction. The methane-containinggas may be a natural gas or a synthetic gas.

[0014] CO-containing polymers of the present invention are formed infree radical polymerization processes using organic peroxides as a freeradical initiator according to conventional methods. Representativeinitiators include dialkyl peroxides such as ditertiary-butyl peroxide,2,5-dimethyl-2,5-ditertiary-butyl-peroxyhexane, di-cumyl peroxide; alkylperoxides such as tertiary-butyl hydroperoxide, tertiary-octylhydroperoxide, cumene hydroperoxide; aroyl proxides such as benzoylperoxide; peroxy esters such as tertiary-butyl peroxypivalate,tertiary-butyl-perbenzoate; and compounds such asazo-bis-isobutyronitrile. Free radical initiators with an appropriatehalf-life at a reaction temperature ranging from about 50° C. to about200° C. can be used, and of these, t-butyl peroxypivalate, which has ahalf life of about 10 hours at 66° C., is preferred.

[0015] Such feeds and initiators are useful for forming CO-containingpolymers under copolymerization conditions at temperatures ranging fromabout 50 to about 230° C., preferably from about 50° C. to about 100°C., pressures ranging from about 100 to about 30,000 psi, preferablyfrom about 100 psi to about 3,000 psi, and in the presence of a freeradical initiator having an appropriate half life.

[0016] Preferably, the reaction occurs in the presence of a solvent.Suitable solvents include toluene, benzene, dioxane, pentane, heptane,hexane, propylene oxide, cyclohexane, and the like. Hexane is preferred.

[0017] The term “polymer” as used herein is a macromolecule formed fromat least one monomer or monomer source; the term “copolymer” is amacromolecule formed from at least two monomers or monomer sources.

[0018] The copolymers and polymers prepared in accord with thisinvention may be recovered from the polymerization of mixture usingconventional methods, for example, by filtration or by evaporation ofthe diluent. They may be brought into the desired shape by the usualforming techniques, such as cold or hot pressing. Alternatively, thepolymerization is carried out in such a way that the copolymer is formedin the desired shape, such as by solution polymerization in a thin layerand subsequent removal of the diluent, which yields the copolymer in theform of a film.

[0019] The number average molecular weight (“Mn”) of the polymers formedin accordance with the invention range from about 200 to about1,000,000. Mn preferably ranges from 300 to 100,000 and more preferablyfrom 500 to 50,000.

[0020] The degree of branchiness of the copolymer chains and the numberof monomer units originating in the monomers with polymerizablecarbon-carbon unsaturation relative to the number of carbon atomsoriginating in carbon monoxide will both, at least in part, determinethe regularity of the polymer chains and thereby also some of theproperties of the copolymer, for example the crystallinity andsolubility. The ratio of the number of monomer units originating in theolefinically unsaturated compound and, if present, the acetylinicallyunsaturated compound to the number of carbon atoms originating in carbonmonoxide is preferably at most about 99:1, more preferably in the rangeof from about 90:1 to about 1:1, and still more preferably from about95:1 to about 1:1. However, where the presence of additional cure sitesare desired or beneficial, the preferred range of acetyleneincorporation should be less than 10%.

[0021] The polymers prepared according to the practice of the inventionare non-linear polymers having a total number of branches per 1000carbon atoms ranging from about 60 to about 300. Branchiness is measuredby ¹³C solution NMR in deutero chloroform using a Cr(AcAc)₃ relaxationagent. The number of C₁ branches per 1000 carbon atoms was measured atabout 20.1 ppm; the number Of C₂ branches per 1000 carbon atoms wasmeasured at about 11.3 ppm; the number of C₃ was measured at about 14.7ppm; and the number of C₄ branches was measured at about 14.2 ppm.

[0022] The polymers prepared in accord with this invention areparaffin-soluble. The term “paraffin” as used herein is a normal, iso,or straight chain alkane.

[0023] The invention is further described in the following non-limitingexamples.

EXAMPLE 1

[0024] A 300 ml autoclave was charged with 150 ml pure n-hexane and0.609 grams of a 75% solution of t-butyl peroxypivalate in mineralspirits. The reactor was sealed and purged with purified nitrogen. Thereactor was initially spiked with ethylene by pressurizing to 170 psigand subsequently pressurizing with multicomponent syngas (MCS) mixture(ethylene 5.4%, carbon monoxide 1.3%, carbon dioxide 7.4%, hydrogen 4.6%and methane 81.3%) to 500 psig. In all examples, relative componentconcentrations are in mole %, unless otherwise noted. The temperaturewas raised to 66° C. while stirring and the autoclave was pressurizedwith MCS feed to 700 psi, which was maintained for 24 hours. The reactorwas allowed to cool to room temperature and was then depressurized. Thehexane was removed on rotary evaporator to obtained 2.58 g the product.

[0025] The product was characterized by IR and GPC. The FTIR spectrum ofthe product showed a very strong peak at 1718 cm⁻¹ due to carbonylgroup, indicating incorporation of carbon monoxide in the product. TheGPC of the product (polystyrene standards, THF solvent) showed the Mn of406 and Mw of 845.

[0026] This example shows that an ethylene feed and a relatively diluteMCS feed are useful polymerization co-feeds.

EXAMPLE 2

[0027] In this example, the polymerization reaction described in Example1 was repeated with a higher level of ethylene spiking, 412 psig initialreactor pressurization compared to 170 psig reactor pressurization inexample 1, in order to gauge the effect of ethylene concentration onproduct molecular weight.

[0028] The product was characterized by IR and GPC. The FTIR spectrum ofthe product showed a very strong peak at 1718 cm⁻¹ due to carbonylgroup, indicating incorporation of carbon monoxide in the product. TheGPC of the product (polystyrene standards, THF solvent) showed the Mn of1000 and Mw of 2550.

[0029] The higher product molecular weight relative to the molecularweight of the product of example 1 shows that ethylene spiking level isan effective method for molecular weight control.

EXAMPLE 3-7

[0030] Carbon monoxide containing polymers was synthesized using an MCSwith a vinyl acetate cofeed using free-radical polymerization. Theseexamples show that ethylene-carbon monoxide copolymers can be formedwith a vinyl comonomer and that molecular weight can be controlled.Polymerization reaction conditions were as follows:

[0031] Any inhibitor present with the vinyl acetate was removed bypassing the vinyl acetate through an inhibitor removal column A 300 mlautoclave reactor was charged with solvent (n-hexane) and a t-butylperoxypivalate initiator. Purified vinyl acetate was added with solventin the autoclave (examples 3 and 6) or added into bomb with the MCS feed(examples 4,5 and 7). The reactor was sealed and purged with purifiednitrogen. The reactor was pressurized to 275 psig with a relativelyimpure (or “dirty”) MCS mixture (ethylene 9.2%, carbon monoxide 21.5%,carbon dioxide 3.0%, hydrogen 55.23%, acetylene 8.01%, and methane3.06%). The temperature was raised to 66° C. while stirring, and thetemperature was maintained for 24 hours, after which the reactor wasallowed to cool to room temperature and was depressurized. The hexanewas removed on rotary evaporator to obtain the product. Table-1 setsforth polymerization details. TABLE 1 Co- Initiator monomer t-butylVinyl Solvent peroxy- Example MCS Acetate Hexane Temp. pivalate YieldNumber Feed (ml) (ml) (° C.) (g) (g) Comments 3 2 10 140 66 0.615 8.5Without bomb 4 2 10 125 66 0.614 10.7 VA added with MCS, with bomb 5 2 5125 66 0.618 6.7 VA added with MCS, with bomb 6 2 5 150 66 0.622 5.0Without bomb 7 2 2 125 66 0.618 2.7 VA added with MCS, with bomb

[0032] Table 2 sets forth characterization results for these polymers.TABLE 2 Example NMR mole % GPC Number Composition (Mn) GPC (Mw) 3 E: 26;VA: 70; CO: 4 1390 6180 4 E: 22; VA: 76; CO: 3 1770 7380 5 E: 32; VA:63; CO: 5 1320 4360 6 E: 39; VA: 55; CO: 5 1070 3270 7 E: 56; VA: 35;CO: 9 730 1620

[0033] In example 4, NMR measurements revealed a double bond consistentwith acetylene monomer incorporation and nonlinear (branched)polyethylene segments.

EXAMPLE 8-10

[0034] Carbon monoxide-containing polymers using a relatively dilute MCScofeed with styrene or 1-octene were synthesized using free-radicalpolymerization as follows:

[0035] An inhibitor removal column removed any inhibitor in the styrene.

[0036] The polymerization conditions were similar to those set forth inExample 1. A 300 ml autoclave was charged with solvent (n-hexane) andt-butyl peroxypivalate initiator. Purified monomer (styrene in examples9 and 10 and octene in example 8) was added with solvent (example 8) inthe autoclave or was added into bomb along with the MCS feed (examples 9and 10). The reactor was sealed and purged with purified nitrogen. Thereactor was pressurized to 700 psig with the MCS mixture. Thetemperature was raised to 66° C. while stirring, and was maintained for24 hours. The reactor was allowed to cool to room temperature, and wasthen depressurized. The hexane was removed on a rotary evaporator toobtain the product. Table-3 sets forth the polymerization details. TABLE3 Initiator Solvent t-butyl Example MCS Co- Hexane Temp. peroxypivalateYield Number Feed monomer (ml) (° C.) (g) (g) Comments 8 1 Octene 150 660.630 2.9 Without bomb 20 g 9 1 Styrene 125 66 0.612 1.5 Styrene added 5g with MCS, with bomb 10 1 Styrene 125 66 0.606 1.9 Styrene added 1 gwith MCS, with bomb

[0037] Table-4 sets forth characterization results for these polymers.TABLE 4 Example NMR mole % GPC Number Composition (Mn) GPC (Mw) 8 8601010 9 B: 30; sty: 70; CO: trace 2380 3450 10 B: 59; sty: 41; CO: trace590 780

[0038] No double bonds indicating acetylene incorporation were observedin the NMR results, consistent with the MCS feed employed.

EXAMPLE 11

[0039] Carbon monoxide containing polymers using an MCS feed with astyrene cofeed was synthesized using free-radical polymerization asfollows:

[0040] An inhibitor removal column removed any inhibitor in the styrene.The polymerization conditions were similar to those set forth in Example3. A 300 ml autoclave reactor was charged with solvent n-hexane andt-butyl peroxypivalate initiator. One gram of purified styrene wasintroduced into the bomb so that it could be added with MCS feed. Thereactor was sealed and purged with purified nitrogen. The reactor waspressurized to 200 psig with the MCS mixture (Ethylene 9.2%, CarbonMonoxide 21.5%, Carbon Dioxide 3.0%, Hydrogen 55.23%, Acetylene 8.01%,and Methane 3.06%). The temperature was raised to 66° C. while stirring,and was maintained for 24 hours. The reactor was allowed to cool to roomtemperature, and was then depressurized. The hexane was removed onrotary evaporator to obtain the product.

[0041] The IR spectrum of the product showed a characteristic carbonylpeak at 1715 cm−1 along with polystyrene peaks. The carbonyl peak in theIR shows that carbon monoxide has been incorporated into the product.

What is claimed is:
 1. A polymerization method comprising reacting afeed under copolymerization conditions, the feed containing anolefinicially unsaturated compound in an amount ranging from about 5 toabout 40 mole %, carbon monoxide is an amount ranging from about 1 toabout 40 mole %, hydrogen in an amount ranging from about 4 to about 55mole %, carbon dioxide in an amount ranging from about 3 to about 10mole %, methane in an amount ranging from about 4 to about 85 mole %,and at least one vinyl comonomer selected from the group consisting offree radical polymerizable vinyl monomers.
 2. The method of claim 1wherein the copolymerization conditions range in temperature from about50 to about 230° C., range in pressure from about 100 to about 30,000psi, and include a radical initiator having an appropriate half life. 3.The method of claim 2 wherein the feed further comprises anacetylinically unsaturated compound in an amount ranging up to about 10mole %.
 4. The method of claim 3 wherein the copolymerization isconducted in the presence of a solvent selected from the groupconsisting of toluene, benzene, dioxane, pentane, heptane, hexane,propylene oxide, cyclohexane, and mixtures thereof.
 5. The method ofclaim 4 wherein the free radical initiator selected from the groupconsisting of ditertiary-butyl peroxide,2,5-dimethyl-2,5-ditertiary-butyl-peroxyhexane, di-cumyl peroxide;tertiary-butyl hydroperoxide, tertiary-octyl hydroperoxide, cumenehydroperoxide; benzoyl peroxide; tertiary-butyl peroxypivalate,tertiary-butyl-perbenzoate; azo-bis-isobutyronitrile and mixturesthereof.
 6. The method of claim 5 further comprising forming the feed ina hydrocarbon conversion process.
 7. The product formed by reacting afeed under copolymerization conditions in the presence of a free radicalinitiator wherein the feed contains an olefinicially unsaturatedcompound in an amount ranging from about 5 to about 40 mole %, carbonmonoxide is an amount ranging from about 1 to about 40 mole %, hydrogenin an amount ranging from about 4 to about 55 mole %, carbon dioxide inan amount ranging from about 3 to about 10 mole %, methane in an amountranging from about 4 to about 85 mole %, and at least one vinylcomonomer selected from the group consisting of free radicalpolymerizable vinyl monomers.
 8. The product of claim 7 wherein thecopolymerization conditions range in temperature from about 50 to about230° C., range in pressure from about 100 to about 30,000 psi, andinclude a radical initiator having an appropriate half life.
 9. Theproduct of claim 8 wherein the feed further comprises an acetylinicallyunsaturated compound in an amount ranging up to about 10 mole %.
 10. Theproduct of claim 9 wherein the copolymerization is conducted in thepresence of a solvent selected from the group consisting of toluene,benzene, dioxane, pentane, heptane, hexane, propylene oxide,cyclohexane, and mixtures thereof.
 11. The product of claim 10 whereinthe free radical initiator selected from the group consisting ofditertiary-butyl peroxide,2,5-dimethyl-2,5-ditertiary-butyl-peroxyhexane, di-cumyl peroxide;tertiary-butyl hydroperoxide, tertiary-octyl hydroperoxide, cumenehydroperoxide; benzoyl peroxide; tertiary-butyl peroxypivalate,tertiary-butyl-perbenzoate; azo-bis-isobutyronitrile and mixturesthereof.
 12. The product of claim 11 further comprising forming the feedin a hydrocarbon conversion process.